Hybrid Electric Vehicles (HEVs) include one or more electric machines driven by inverter systems and may include an internal combustion engine. A high voltage battery is used in the electrified powertrain to supply power to the electric machines and to store energy recuperated during vehicle braking. The electric motor/generator(s) within a hybrid electric vehicle provides additional degrees of freedom in delivering the driver-demanded torque and may also be used to control the output speed of the engine.
It is known that a boost converter may be used in hybrid powertrain systems for increasing voltage to control the one or more electric machines while allowing for a reduction in the number of cells needed in the vehicle battery back. The basic principle of a boost converter consists of an input side, an output side, switches and three distinct operating states including a bottom-switch-on-state, a top-switch-on-state, and both-switches-off-state. During the bottom-switch-on-state, the bottom switch is closed resulting in a change in positive direction in the inductor current. During the top-switch-on-state, the top switch is closed and the bottom switch is opened allowing the inductor current to change direction and travel through the top switch to the output side. The switching between these two states results in higher voltage on the output side than input side. To avoid both switches turning on at the same time, a both-switches-off-state is implemented to insert a delay in time between one switch closing and the other switch opening. This delay between the switch states is called deadtime.